In new construction, whether for commercial, residential, industrial, bridge, road, or other uses, it is often necessary to extend a pipe or conduit for water, gas, electrical line, etc. through a wall, or a floor. Furthermore, it is frequently desirable or even mandatory to provide a hydrostatic seal around the pipe or conduit to preclude seepage of water or other fluid through the wall or floor. The most practical and effective seal construction for applications of this kind, in most instances, is an expansion seal formed of a series of interleaved blocks of rubber or other elastomer interconnected by a sequence of pressure plates, with a plurality of.bolts extending between the pressure plates; the bolts are tightened to squeeze the elastomer blocks between the pressure plates, expanding the blocks to form a continuous hydrostatic seal around the periphery of the pipe. A preferred construction for a wall seal closure of this kind is described and claimed in U.S. Pat. No. 3,528,668 of Bruce G. Barton. Other wall closure seal constructions for forming peripheral seals on pipes and conduits are also known in the art.
To assure an effective seal, in applications of this kind, it is highly desirable and often necessary to form an opening in the wall or floor, through which the pipe or conduit can extend, with an internal diameter large enough to afford an essentially symmetrical annular space between the pipe and the opening. The diameter of the wall opening may vary to a substantial extent, depending upon the outside diameter of the pipe or conduit and the particular seal to be used. Thus, the internal diameter required for the wall opening may range from under two inches up to two feet or more. For most construction of this kind, particularly in a concrete wall, a wall sleeve extending through the concrete is employed.
One practical and effective wall sleeve construction that has seen widespread use in applications of this kind is a metal tube having a length equal to the width of the wall and having a metal ring welded to the outside central portion of the metal sleeve. The metal ring serves as a water stop to preclude water seepage along the outer surface of the sleeve, at the interface between the sleeve and the concrete wall. The ring also serves as an anchor to preclude axial movement of the wall sleeve relative to the wall. This metal sleeve construction, however, presents difficult technical problems of a continuing nature relating to accurate location of the sleeve, prevention of entry of concrete or debris into the sleeve, and the need to maintain a substantial inventory of sleeves of differing lengths; the wide variations in wall width and in required sleeve diameter produce too many combinations for economical storage. Further, corrosion and sleeve weight are continuing problems.
Another advantageous wall sleeve construction, one which effectively overcomes many of the disadvantages of steel wall sleeves, is disclosed in U.S. Pat. No. 4,625,940 of Bruce G. Barton. That wall sleeve construction starts with a molded resin precursor having cup-like end cap sections of an outside diameter D formed integrally with the opposite ends a main sleeve section having an inside diameter D; the end cap sections are ends of the main sleeve section by hollow transition sections of larger diameter. In use, the end caps are cut off the main sleeve and mounted in a concrete form, with the sleeve section slipped into the two cap sections. When the wall has been poured and set, the end caps are removed along with the form walls, leaving a wall sleeve suitable for use with a conduit and expandable seal, as described above.
The wall sleeve precursors of U.S. Pat. No. 4,625,940 can be used to produce a wall sleeve longer than an individual precursor by cutting off the end wall of a cap section on one sleeve precursor and inserting it into the end of another precursor from which the complete cap section has been removed. But the resulting extended length sleeve leaves much to be desired. At best, if the two precursors are joined by a thermal weld (it is quite difficult to form such a weld joint) there is a ridge inside the joint and an appreciable length of a reduced diameter within the sleeve. The joint is not usually as strong as desired. Usually, auxiliary fasteners such as self-tapping screws are needed, with messy external sealant needed. More importantly, the screws or other fasteners project into the sleeve and create an appreciable obstruction in it. Moreover, the labor expense is substantial, and scrap is usually undesirably high. The present invention is an improvement on that of the Barton U.S. Pat. No. 4,625,940.